Longevity of seemingly fragile seeds studied

Updated 9:55 am, Monday, May 28, 2012

Most seeds, including these milkweed seeds, lie dormant for most of a year or even longer before germinating.

Most seeds, including these milkweed seeds, lie dormant for most of a year or even longer before germinating.

Photo: Forrest M. Mims III, For The Express-News

Longevity of seemingly fragile seeds studied

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After writing a recent column about the germination of very old seeds, I discussed seed dormancy with professor Alan Lievens, chairman of the biology department at Texas Lutheran University in Seguin. Lievens is uniquely qualified in his field, since he holds doctorates in both medicine and biology.

Lievens told me about an amazing experiment begun 133 years ago that was described by Kathryn Brown in the March 2001 issue of the journal Science. This unique experiment is a story worth telling.

For several decades, professor William Beal was one of the leading botanists in the United States.

In 1879, Beal began a most unusual project. He collected 1,000 seeds from each of 20 species of plants. He then divided the seeds into 20 lots, each containing 50 seeds. Next, he mixed each batch of seeds with damp sand and packed each mixture into a clear glass bottle without a lid or cork. He buried all 20 bottles, with their open end down, in a row at the campus of the Michigan Agricultural College. Beal's plan was to dig up a bottle of seeds every five years to determine how many would germinate.

Much has changed since 1879 at Beal's college, which is now Michigan State University. Beal died in 1924, but his experiment is still very much alive. The number of seedlings that germinated from each bottle fell over the years. Eventually a decision was made to stretch the interval between unearthing bottles from five to 10 and eventually 20 years. Eighty years after the experiment began, botanists were pleasantly surprised when that year's bottle produced seedlings of curled dock, evening primrose and moth mullein. Moth mullein is a European plant that produces yellow flowers. After 90 years, only moth mullein seeds germinated. The latest phase of the experiment occurred in 2000, when the 15th excavated bottle yielded 25 plants from its 121-year old seeds. All but a few were moth mullein. The sixteenth bottle will be excavated in 2020, and the experiment will close when the final bottle is dug up in 2100.

Many seeds can emerge from a dormant state after a few years, but some species of plants produce especially long-lasting seeds. Botanists are actively studying how the seemingly fragile seeds of some plant species can survive a century or more.

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Ongoing scientific studies were begun well before Beal's unique experiment, including regular observations of tides, weather, sunspots, comets, planets and stars. But the longevity of Beal's Rip Van Winkle experiment is among the longest in biology.